Ultrasonic diagnostic apparatuses which are subject information acquisition apparatuses have been widely used in medical sites, for example. Such apparatuses are applicable widely and are aimed for many regions including the heart.
A blood pressure is importantly measured in heart disease inspections and diagnoses. Methods for measuring a blood pressure which are performed in real medical sites may include a bloodless measurement to be performed by winding a cuff around an upper arm, for example, and a bloody measurement to be performed by inserting a catheter into a blood vein.
PTL 1 discloses a method for measuring endocardial pressure by injecting an ultrasonic contrast medium (hereinafter, simply called a “contrast medium”) containing fine bubbles into a blood vein and analyzing a frequency distribution of a signal component based on reflected waves from the contrast medium.